Here, we highlight some of the lesser-known symptoms which could be signs of sleep apnea …

Frequently waking to urinate

Waking up to urinate twice or more per night could be a sign of sleep apnea.

Medical professionals are increasingly using how often you wake to urinate as an unofficial screening test for sleep apnea. The exact mechanisms of the link are unknown, though there are three proposed reasons.

Firstly, it is thought that the frequent exertions and efforts during an apnea episode increase abdominal pressure, in turn, putting pressure on the bladder [1].

Second, the arousals experienced with sleep apnea can make you more aware of a perfectly normal need to urinate. Most people can sleep for many hours without needing to urinate as sleep does a good job of suppressing the mental urge. Only when we wake do we acknowledge this need.

Lastly, whilst the connection is not fully studied, a hormone released by heart during apnea episodes also influences the kidneys, increasing the need to urinate.

The science bit – what is this hormone?

Atrial natriuretic peptide (ANP) is a hormone released in the right atrium (one of the four chambers of the heart) in response to increased blood pressure, low-oxygen events and constriction of blood vessels in the heart – all seen during an apnea episode. It acts to dilate these blood vessels to take pressure off of the heart and other organs. ANP acts systemically, meaning it gets into the bloodstream where it can reach other areas of the body and make changes. ANP therefore also helps to reduce blood pressure by increasing urine output via a number of actions in the kidneys [2].

Mood changes

A lack of good quality sleep can affect your mood in the short term and long term.

Depression, anxiety, short temper, irritability – these are symptoms of sleep deprivation, one of the most damaging aspects of sleep apnea. This mental decline can be both an immediate and long-lasting complication.

Sleep apnea is known to increase the likelihood of many physical conditions (diabetes, stroke, heart failure etc.) but there is also evidence to show that sleep apnea also poses an increased risk of depression, bipolar affective disorder and other mood disorders.

A recent cohort study in Taiwan followed 32,000 people with and without sleep apnea. 1.13% of the non-sleep apnea group were diagnosed with a mood disorder compared to more than double (2.84%) in the sleep apnea group [3].

Dry mouth

Frequently waking with a dry mouth is a potential indicator of sleep apnea.

Another unofficial screening question in medical consultations on sleep apnea, patients are often asked if they wake up with a dry mouth.

In a recent study, 668 patients referred to a sleep clinic and suspected of having sleep apnea were asked how often they experienced waking with a dry mouth. Those with confirmed sleep apnea were twice as likely to have a dry mouth “almost always” compared to those without sleep apnea [4].

“The prevalence of dry mouth upon awakening was twofold higher in patients with OSA (31.4%) than in primary snorers (16.4%, P < 0.001), and increased linearly from 22.4%, to 34.5%, and 40.7% in mild, moderate, and severe OSA respectively (P < 0.001).”

A plausible explanation for this is that sleep apnea sufferers open their mouth more frequently during the apnea episodes, where the characteristic sharp intake of air necessitates a big gulp through the mouth.

This correlation could also be the reverse, whereby people are experiencing sleep apnea because they are already habitual mouth-breathers.

Low sex drive

Obstructive sleep apnea can negatively impact upon the sex lives of both men and women.

Many studies have linked sleep deprivation from OSA with decreased sexual desire in both sexes [5]. Scientists suggest that the effects of sleep disruption on the hormone testosterone is partly to blame [6].

Testosterone – a steroid sex hormone – naturally increases with sleep. The lack of quality sleep seen in OSA reduces testosterone production. Hence, libido in both men and women, and sexual performance in men is negatively affected [7].

A study in 2009 found that 70% of men referred for sleep apnea treatment also had treatment for erectile dysfunction [8].

Acid reflux

There is a significant relationship between acid reflux and sleep apnea [9].

Acid reflux (sometimes referred to as gastro-esophageal reflux disease or GERD for short) is a condition where the acidic contents of the stomach cause irritation when they move back up into the esophagus.

There are competing theories as to whether acid reflux is a result of sleep apnea or vice versa. Nonetheless, it is estimated that more than half (58-62%) of patients with sleep apnea also experience acid reflux disorder, though this is thought to be at least somewhat attributable to obesity.

The exact mechanics of this link are uncertain, but there is some evidence to suggest that the pressure changes in the chest during apnea episodes can produce reflux symptoms.

Despite this uncertainty, treating sleep apnea has positive knock on effects for reflux. The reverse has also been demonstrated whereby drugs for acid reflux reduce apnea episodes [10].

Conclusion

The classic signs of sleep apnea are loud snoring, sleepiness, headaches and sore throat. There are many more symptoms and complications, some minor, and some that are problematic conditions in their own right.

Sleep apnea often goes undiagnosed. A lack of understanding and social stigma surrounding snoring are big reasons for this. It is important to be able to spot the lesser-known signs to help you make sense of your symptoms and seek the most appropriate course of treatment.